This invention relates to a process for recovering primary normal aliphatic higher alcohols from surgarcane, or products obtained from the sugarcane, or processed products from production of sugar, more particularly by extraction using a fluid in a subcritical or supercritical state as an extractant.
Among primary normal aliphatic higher alcohols, octacosanol of C.sub.28 and triacontanol of C.sub.30 are important from the viewpoint of utility. Octacosanol is a linear saturated monohydric alcohol represented by the molecular formula CH.sub.3 (CH.sub.2).sub.26 CH.sub.2 OH with the molecular weight of 410.74 and the melting point of 83.2.degree. to 83.4.degree. C. in a white crystalline state and exists as one component of vegetable wax, such as extracted from wheat blades, wax covering the rinds of apples, candelilla wax, cotton wax, etc. in the nature, and also widely distributes in vegetable oils, cereals, nuts, leaves and steams of plants, rinds of fruits, etc., but its content is a trace amount, for example, an order of 10 to 20 ppm.
It is known that octacosanol has two major effects, i.e. increase in physical stamina and remedy of damaged nerve cells, and also has the following particular functions and effects:
(1) Increase in endurance, vitality and physical stamina, PA1 (2) Improvement of reflect action and quick action, PA1 (3) Increase in resistance to stress, PA1 (4) Stimulation of sex hormone and decrease in myospasm, PA1 (5) Improvement in functions of muscles including myocardium, PA1 (6) Decrease in systolic blood pressure, and PA1 (7) Increase in basal metabolism.
Octacosanol is thus used in health food or for therapeutic purpose. It is appropriate to administer 1 mg/day for the ordinary increase in physical stamina, but it is better for the therapeutic purpose to administer about 40 mg/day through addition thereof to minerals or vitamins.
Triacontanol is also called melissyl alcohol and is a linear saturated monohydric alcohol represented by the molecular formula CH.sub.3 (CH.sub.2).sub.28 CH.sub.2 OH with the molecular weight of 438.80 and the melting point of 86.5.degree. C. in a white crystalline state. Triacontanol as well as octacosanol is contained in trace amount as one component of vegetable wax in the nature. It is known that triacontanol has the similar effects to those of octacosanol, and further a very remarkable effect on plant growth.
Such useful octacosanol can be obtained by chemical synthesis from behenic acid CH.sub.3 (CH.sub.2).sub.20 COOH as a starting material, by electrochemical reaction of 1,18-octadecane-dicarboxylic acid monoethyl ester obtained from cyclohexane and butadiene with capric acid, or by extraction from natural vegetable oil, wax, etc.
Among natural vegetable oil, wax, etc., it is known that wheat germ oil contains about 100 ppm of octacosanol, and thus is said to be most suitable raw material for commercial scale extraction owing to its high content.
Triacontanol can be synthesized by the same electrochemical reaction as used to synthesize octacosanol, using lauric acid in place of capric acid. However, no commercial scale extraction of triacontanol from vegetable wax has been carried out yet.
Chemically synthesized octacosanol seems to have the same effect as the natural octacosanol, but it is difficult to obtain behenic acid itself as a raw material for the synthesis, and also the electrochemical procedure involves complicated synthesis step and purification step, leading to a higher cost. Furthermore, chemically synthesized octacosanol still has a fear of adverse effect on human bodies in administration because of chemically synthesized product.
Natural octacosanol is contained as much as 100 ppm in the wheat germ oil which is said to have the highest content, and only a trace amount of octacosonal is contained in other natural vegetable materials. Furthermore, octacosanol is insoluble in water, and also has a low solubility in organic solvents. That is, its extraction is very difficult to carry out and is very expensive. This is also substantially true of triaconstanol.
Separation of organic compounds from their mixtures with a fluid in a subcritical or supercritical state is disclosed, for example, in Japanese Patent Publication No. 54-10539 (=U.S. Pat. No. 3,969,196).
The fluid in a subcritical or supercritical state is a fluid approximately at the critical temperature and a critical pressure or at higher temperature and pressure than the critical temperature and critical pressure. For example, it is a fluid approximately in a critical state or supercritical state such as ethylene around 9.9.degree. C. and 50 atm, carbon dioxide around 31.0.degree. C. and 72.9 atm, which has a density approximating to that of a liquid and a high diffusion coefficient approximating to that of a gas. Owing to these characteristics, various compounds can be rapidly and efficiently extracted in high yield, and separation of the extractant can be carried out with ease. Furthermore, solubility of various compounds can be largely changed by slightly changing the pressure and temperature, and thus enables selective extraction to be carried out. However, a process for recovering primary normal aliphatic higher alcohols from sugarcane, or products obtained from the sugarcane, or processed products from production of sugar by using a fluid in a subcritical or supercritical state as an extractant has not been disclosed yet.